Thinking about buying a used PC? Before parting with your hard-earned dollars, run a diagnostic check on the system's motherboard components. Chip-level problems such as a bad RAM module, a faulty clock chip, or a damaged serial port aren't always easy to detect, and they definitely aren't easy to repair. Windsor Technologies' $US10 TuffTest is an excellent diagnostic utility for BIOS-level devices. ItÆs located on this monthÆs CD and you can contact the company at www.windsortech.com.